In many engines with fuel injection systems it is desirable to supply liquid fuel to the fuel injector or injectors at a substantially constant pressure. In a no return fuel delivery system, when the engine is not consuming fuel, fuel remains in the fuel lines, fuel pressure regulator, and in the fuel rail connected to the fuel injectors. During normal operating conditions the fuel rail becomes heated and tends to heat the fuel therein causing that fuel to expand.
U.S. Pat. No. 5,458,104 discloses an accumulating fuel pressure regulator with a diaphragm capable of being displaced to accommodate expansion of the fuel. This system has a manifold reference to maintain a constant pressure drop across the fuel injectors. In this system, if the diaphragm ruptures liquid fuel can be emitted from the regulator onto the manifold or other heated engine components creating a potentially hazardous situation. To avoid this hazard, two diaphragms are needed to prevent fuel from being emitted from the regulator onto the heated manifold or other engine components if the first diaphragm ruptures.
In other systems the fuel pressure regulator is referenced at or near atmospheric pressure. Additional features are also needed in these fuel pressure regulators to prevent fuel from being emitted from the pressure regulator and onto heated engine components. Further, in previous systems a spring has been used to bias the diaphragm and when the system becomes heated the spring force decreases due to the rise in temperature permitting the diaphragm to be more easily displaced thereby further increasing the volume of the fuel chamber of the pressure regulator. This reduced spring force decreases the pressure at which the fuel is delivered to the fuel injectors and thereby undesirably affects the performance of the fuel injectors and hence, the engine.